Re: Extra Terrestrials

From: Russell Standish <>
Date: Thu, 3 Aug 2000 10:36:53 +1000 (EST)

Alastair Malcolm wrote:
> From: Russell Standish <>
> > I've just finished reading "Extraterrestrials: Where are they?" by
> > Zuckerman and Hart. It really scotches the idea that SETI might
> > actually be successful, even though the Fermi paradox is a bit
> > overdone "Any ET civilisation of substantial duration would have
> > colonised the Galaxy by now. So where are they?"
> >
> > However, Gott raises an interesting point. Anthropic reasoning eg
> > Doomsday argument really rules out galactic colonisation - at least
> > for our reference class. It would appear that the Doomsday argument is
> > in direct contradiction with the Fermi paradox. I am rather
> > uncomfortable about this, and my preference would be to accept the
> > Fermi paradox argument over the anthropic reasoning.
> I must be missing something here. Isn't the obvious answer for both Doomsday
> and Fermi that civilisations don't last long enough to colonise?

Yes, sorry. It was a case of meaning something, and saying something
quite different. I really mean Fermi + a lot of other stuff in the
book countering the physical and sociological responses such as the
ones you just mentioned imply that we as humans, or our "intellectual
descendents" will end up colonising the Galaxy. Therefore, surely the
density of observers should be much greater during a Galactic
civilisation epoch.

I suspect that the answer may be found in resolving the reference
class problem of the DA. It probably won't be humans that colonise the
Galaxy, but our descendents, whatever they may be.


> Standard responses to the Fermi paradox include self-destruction,
> colonisation apathy, and clandestine spread in our area (for ethical or
> scientific reasons). My own favoured explanation is simply that intelligent
> life (not necessarily any life) is sufficiently rare (<1 per galaxy) that
> visitations haven't happened yet. There are counters to DA.
> Alastair

Dr. Russell Standish Director
High Performance Computing Support Unit, Phone 9385 6967
UNSW SYDNEY 2052 Fax 9385 6965
Room 2075, Red Centre
Received on Wed Aug 02 2000 - 17:32:18 PDT

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